ASN database support

[athiede-vendavo]

Describe the bug
Helm chart lacks support for ASN databases - recent graylog (and/or plugin update) added support for GeoLite2-ASN database.

It would be nice if the chart had a key for the ASN database as well as the existing geoip.mmdbURI key.

Version of Helm and Kubernetes:

Helm Version:

14:52 $ helm version
version.BuildInfo{Version:"v3.9.0", GitCommit:"7ceeda6c585217a19a1131663d8cd1f7d641b2a7", GitTreeState:"clean", GoVersion:"go1.18.2"}

Kubernetes Version:

14:52 $ kubectl version
WARNING: This version information is deprecated and will be replaced with the output from kubectl version --short.  Use --output=yaml|json to get the full version.
Client Version: version.Info{Major:"1", Minor:"24", GitVersion:"v1.24.1", GitCommit:"3ddd0f45aa91e2f30c70734b175631bec5b5825a", GitTreeState:"clean", BuildDate:"2022-05-24T12:17:11Z", GoVersion:"go1.18.2", Compiler:"gc", Platform:"darwin/arm64"}
Kustomize Version: v4.5.4
Server Version: version.Info{Major:"1", Minor:"23", GitVersion:"v1.23.5", GitCommit:"8211ae4d6757c3fedc53cd740d163ef65287276a", GitTreeState:"clean", BuildDate:"2022-03-31T20:28:03Z", GoVersion:"go1.17.8", Compiler:"gc", Platform:"linux/amd64"}

Which version of the chart:
graylog-2.1.3

What happened:
Updated graylog image to 4.3.1-1 and saw the following in logs:

2022-06-01 19:41:50,415 WARN [MaxMindIpResolver] - Error creating DatabaseReader for 'MaxMindIpAsnResolver' with config file '' - {}

What you expected to happen:
either no log errors or a configuration option for the second database

How to reproduce it (as minimally and precisely as possible):
install chart, see nothing populated in graylog configuration for ASN DB

Anything else we need to know: